GTK-Doc

GTK-Doc is a software tool that is designed to document C code. It is commonly used to document the public API of libraries such as the GNOME and GTK+ libraries, but it is also suitable for documenting application code. However, it should be noted that GTK-Doc was not originally intended to be a general-purpose documentation tool, and thus, it may be a bit difficult to set up and use at first.

If you're looking for a more polished general-purpose documentation tool, Doxygen may be a better option. Nevertheless, GTK-Doc has some unique features such as special code that can document the signals and properties of GTK+ widgets and GObject classes that other tools may not have.

GTK-Doc offers two ways to write your documentation: first, embedded in the source code in specially formatted comments, or second, added to the 'template' files that GTK-Doc outputs after scanning all header files and parsing the declarations.

By using these source code comments and template files, GTK-Doc generates a Docbook XML (or SGML) document that is then transformed into HTML. This HTML documentation can be browsed on an ordinary web browser or by using the special Devhelp API browser. Therefore, if you need to document C code quickly and accurately, GTK-Doc is an excellent choice.